System-Powered Controls with Pneumatic Interface

PNEUMATIC SEQUENCED HEATING/COOLING (HOT WATER) Ð By using a 20 psi pneumatic source, one ther- mostat can control both heating and Moduline cooling in the conditioned space. The pneumatic circuit is interfaced with the system-powered circuit by use of a pilot valve. In cool- ing, the Moduline air¯ow is controlled by the duct-powered volume controller just as in all system-powered control. As the schematic diagram shows, a DA pneumatic wall ther- mostat working through the pilot valve, replacing the system- powered thermostat, modulates the pilot valve and thus the volume controller low side pressure.

Figure 75 shows the piping diagram. Figure 76 shows the sequence diagram for a direct acting thermostat with a nor- mally open pilot valve. With the system shut down and the space temperature low, at start-up the thermostat branch pres- sure is low, and the normally open water valve (or other heat- ing means) is open. As the space temperature rises, the branch pressure rises, modulating the water valve to a closed po- sition. The pilot valve is normally open, with set point above water valve spring rate, thus maintaining a low pressure in the low side of the volume controller, closing the bleed valve in the controller and raising the bellows pressure to the duct pressure level; this results in unit shutoff.

If the space temperature continues to rise, the NO pilot valve will modulate toward closed, raising the low side pres- sure, opening the bleed, reducing the bellows pressure, and opening the Moduline unit air valve. The air¯ow will rise until the volume controller setting is reached.

Note that the spring rates of the hot water valve and the pilot valve must be properly matched to accomplish the ac- tion described above.

A heating/cooling sequence can also be accomplished with a reverse acting circuit (Fig. 77 and 78). At start-up, the tem- perature is low, the branch pressure is high, and normally closed water valve is wide open. As the space temperature rises, the branch pressure falls and the water valve closes, stopping the heating supply. The pilot valve is NC and thus at branch pressures above its setting will open, volume con- troller low pressure will be reduced, the bellows pressure will rise and the unit will shut off.

LEGEND FOR FIG. 75 - 78

DA

Ð Direct Acting

NC Ð Normally Closed

HW

Ð Hot Water

NO Ð Normally Open

M

Ð Main

RA Ð Reverse Acting

Fig. 75 Ð Piping Diagram, Heating/Cooling

Sequence, DA Thermostat

Fig. 76 Ð Sequence Diagram Ð DA Thermostat

Fig. 77 Ð Piping Diagram, Heating/Cooling

Sequence, RA Thermostat

Fig. 78 Ð Sequence Diagram, RA Thermostat

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Carrier 37HS specifications System-Powered Controls with Pneumatic Interface
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37HS specifications

The Carrier 37HS is a cutting-edge heating, ventilation, and air conditioning (HVAC) solution designed to deliver exceptional performance and energy efficiency for residential and commercial applications. This unit is particularly favored for its advanced features and reliable operation, making it a popular choice among homeowners and building managers alike.

One of the standout characteristics of the Carrier 37HS is its high Seasonal Energy Efficiency Ratio (SEER), which indicates its ability to provide effective cooling while minimizing energy consumption. This makes it not only cost-effective but also an environmentally-friendly choice, helping to reduce the overall carbon footprint. The unit is equipped with state-of-the-art inverter technology, which allows it to adjust its cooling capacity to match the current demand, thus enhancing comfort while optimizing energy use.

The Carrier 37HS incorporates a high-efficiency scroll compressor that operates quietly and efficiently. This technology enhances the unit's reliability and longer service life while ensuring minimal noise levels during operation, making it suitable for residential settings where tranquility is paramount.

A significant feature of the 37HS is its variable-speed fan system, which enables gradual adjustments in airflow to maintain a consistent and comfortable indoor environment. This not only contributes to enhanced comfort but also reduces wear and tear on the system, further extending its longevity.

Moreover, the Carrier 37HS is designed with advanced air filtration capabilities, utilizing multi-stage filters that capture airborne particles, allergens, and pollutants. This results in improved indoor air quality, making it an ideal choice for those with allergies or respiratory issues.

The unit also boasts user-friendly smart controls, allowing homeowners to monitor and adjust settings remotely via a smartphone app. This feature adds convenience and assists in energy management, ensuring that users can optimize their HVAC system even when they are away from home.

In summary, the Carrier 37HS stands out for its exceptional energy efficiency, quiet operation, advanced technology, superior air filtration, and modern smart controls. These features collectively make it a prime solution for those seeking a reliable HVAC system that delivers both comfort and savings, while also contributing positively to environmental sustainability. Whether for a residential setting or a commercial establishment, the Carrier 37HS is engineered to meet a variety of climate control needs with excellence.
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